Centrifugal switch



H. R. CANFIELD.

CENTRlFUGAL SWITCH.

APPLICATION FILED NOV. 6, 1919.

1 ,362,600 Patented Dec. 21, 1920.

2 SHEETS-SHEET I.

H. R. CANFIELD.

CENTRIFUGAL SWITCH.

APPLICATION FILED NOV. 6. 1919.

1,362,600. Patented Dec. 21, 1920. t

2 SHEETSSHEET 2.

UNITED STATES PATENT OFFICE.

HARRY a. CANFIELD, or CLEVELAND, onro, JASSJYIGNOB, TO THE OHIO ELECTRIC AND conrnormnn compan or CLEVELAND, OHIO, A CORPORATION or OHIO.

CENTRIFUGAL SWITCH.

To all whom it may concern:

Be it known that I, HARRY R. CANFIELl), a citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio have inventeda certain new and useful Improvement in Centrifugal Switches, of which the following is a full, clear, and exact description, reference being had to. the accompanying drawings.

This invention relates to centrifugal electrical switches and more particularly to switches of the type commonly used on small single phase or split phase motors to automatically open the auxiliary starting winding of the motor when the motor has attained a pre-determined speed.

.One of the objects of my invention is to provide a centrifugal switch consisting of few parts, of simple .construction, which shall be easy to manufacture and assemble.

Another object is to provide a switch which shall be positive in operation and have great durability under wear.

.Another object is to provide a switch having stationary and movable contacting parts which shall be self alining and therefore make contact at all times, even after considerable wear, without the necessity of special care in manufacturing and assembling.

Another object is to provide an improved switch of this class which can be assembled into a ball bearing mo'tor without interfering with the assembly of the ball bearings in the most approved manner.

In the accompanying drawings wherein I have shown certain illustrative embodiments of my invention but without'intent to limit myself thereto, Figure 1 is a side elevation of a ball bearing motor, with parts broken away to show my invention applied thereto; Fig. 2 is a. detailed sectional view, showing the method'of assembling the ball bearing and the 'switch; Fig. 3 is a section taken on the line 3-3 of Fig. 2; Fig. 4 is a perspective view of my centrifugal switch with the parts in position for assembly and Figs. 5 and 6 are modifications of the method of mounting the movable contact.

Describing the various parts by reference numerals, 1 indicates the supporting plate preferably formed of my device which is b means of suitable dies to the desired siiapepThershajt collar 2, the stop lug 3,

66'and the supporting lugs 4 and 5 are all Specification of Letters Patent. P t t 21, 1' 2 Application filed November 6, 1919. Serial No. 336,094.

away upper portion and the brush block parts. The insulating arm and the movable contact member or brush block when assembled are generally known as the contactor.

The brush block is adapted to bridge'the rings 12, 12 and complete the circuittherebetween. The rings 12, 12 are mounted on an lnsulating sleeve such as the bakelite sleeve 14 which is supported by the flange 16'formed integral with the motor casing. In assembling the parts on the motor shaft, the supporting plate 1 is forced on the shaft to the position indicated in Fig. 2 and held there by frictional contact of the collar 2 with the shaft. he bearing assembly is then placed on the shaft as follows: a throw ring 17, a felt washer 18 and a second throw ring 19 are placed on the shaft to form a suitable sealing for the bearin against loss of oil and accumulation 0 dust in the bearin The inner ball race 20 is now forced on t e reduced end of the motor shaft and the ball cage assembly 21 snapped in place on the race. The motor shaft is now pushed into the bearing as shown in Fig. 1 until the balls rest in the .outer race 22.

If the motor is now connected to a single phase alternatin circuit, the current will dlvide and part ow through the main field .winding and part through ring 12 across 10 serves to draw the brush block 7 against the two rings 12, 12 as the motor shaft comes to rest.

When the current cal circuit therebetween, and also self alining with respect to the contour of the stationary contacts which assures a maximum bearing surface at all times. This is secured by the, link connections shown, although it is obvious that any type of oint which will permit universal movement' would serve equally well. These features readily adapt my switch to quantity production since no special care has to be. taken to accurately position the rotating block on the stationary contacts during the assembly of the parts.

The insulating arm 8 and brush block 7 are so shaped and assembled that a line connecting the two points at which the arm 8 is suspended will lie between the center of gravity of these parts and the center ofv rotation of the support 1. This allows the brush block 7 to leave the rings 12, 12 evenly when the centrifugal force acts thereon and permits a break with each ring simultaneously thereby distributing the current flow to two points of lbreak and minimizing any races.

tendency to are. 3

it will also be noted that the brush block is held under tension sufficient to insure good contact with the rings 12, 12 but the tension means is so positioned that when the block 7 is out against the stop lug 3 the tension is not materially increased and a force sufficient to break the contact is substantially sufficient to carry the block 7 out against lug 3 which gives it a snap action rather than an undesirable sluggish movement. A

The brush block is preferably a graphite carbon composition and the rings 12, 12 are preferably copper, since this combination will be noiseless in operation and wear between them is reduced to a minimum, thereby insuring a switch action at the same motor speed at all times.

The construction of my switch also permits me to mount the inner ball race, with ball cage thereon, tightly to the motor shaft and the outer race tightly in the motor casing, so that when the bearing is completely assembled, the rotation will be entirely between the ball cage and inner and outer This is a decided advantage since heretofore it has been necessary to assemble the bearing complete in the motor casing and then insert the shaft in the inner-race which allows a certain amount of rotation to take place between the shaft and the innetrace which results in subsequent wearing and wabbli-ng of the motor shaft.

The wires 24.24;, leading from the auxiliary winding to the rings 12, 12 are preferseveral thicknesses answers the purpose in all respects.

In Figs. 5 and 6 I have shown slight modifications in my method of floating the brush. block. In Fig. 5 I have shown the insulating arm 8 linked as at 23 and the brush block 7 held in contact with rings 12, 12 by the spring 10 positioned on the same side as the link. Fig. 6 shows the brush block 7 and a suitable shaped insulator 8 supported between two springs 10-10.

lt will be understood that the foregoing are only a few of the many physical forms in which my invention can be embodied and that many changes can be made within the scope of my claims.

Having thus described my invention, what l claim is A centrifugal switch comprising a plurahty of stationary contacts and a rotary contact adapted to complete the electrical connection therebetween, a non-conducting member attached to said rotary contact, a support for said non-conducting member having a universal connection and a resilient universal connection to said non-conducting member, and means for rotating said support whereby said electrical connection is broken at a predetermined speed.

2 A centrifugal switch comprising a plurality of stationary contacts and a rotary contact adapted to complete the electrical connection therebetween, a non-conducting member attached to said rotary contact, a support for said non-conducting member having a universal connection and a resilient universal connection to said non-conducting member, said points of connection being on a -line lying between the center of gravity of said rotary contact and the center of rotation of said support and means for rotating said support whereby said electrical connec tion is brokenat a predetermined speed.

3. A centrifugal switch comprisinga pair of stationary copper rings, a single universally and resiliently supported graphitic carbon contact adapted to electrically connect said rings, and means for rotating said contact on said rings whereby said connection isbroken at a predetermined speed.

4. In a motor, a casing, a cylindrical flange on said casing, an insulator on said flange, a

pair of stationary coaxial cylindrical concylindrical contacts when said motoris rota-t ing below a predetermined speed,

6. In a motor, a casing, a cyhndrlcal flange on said casing, an insulator on said flange, a

pair of stationary coaxial cylindrical contacts of equal diameter on said insulator, rotatable contact adapted to electrically connect said cylindrical contacts when said motor is rotating below a predetermined speed, a flexible motor circuit wire connected to each of said cylindrical contacts and a sensirigid sleeve on each of said wires whereby said wires are held out of the path of movement of said rotatable contact.

7. A centrifugal switch comprising a supporting element provided with a stop member and adapted to be fastened to a motor shaft, a non-conductor.capable of universal @movement fastened to said supporting ele- Inent, a conductor fastened to said non-conductor and adapted to bear on a plurality of stationary conductors when said shaft is at rest and engage said stop member when said shaft is rotating above a predeterminedspeed.

'8. A centrifugal switch comprising a supporting element provided with a stop memer and adapted to be fastened to aniotor shaft, a non-conductor capable of unlversal movement fastened to said supporting ele nient, a conductor fastened'to said non-conductor, means for counterbalancing the weight of said support and said parts attached thereto, said conductor being adapted to bear on a plurality of stationary conductors when said shaft is at rest and engage said stop member when said shaft is rotating above a predetermined speed.

9. A centrifugal switch comprisingla supporting element adapted to be fastened to a motor shaft, a non-conductor provided with 10. In a device of the class described, the

combination with a plurality of circular stationary insulated conductors, of means for completing the circuit therebetween when the motor shaft is at rest and opening said circuit when said shaft is rotating above a predetermined speed, a ball race rigidly fastened to said shaft, a ball cage mounted on said race, said stationary conductors being of such size as to permit the passage of said ball cage'therethrough when the parts are being assembled. I J

In testimony whereof, I herednto aflix my signature.

' HARRY R. CANFIELD. 

